swift变量

值类型：字符串，数组，字典，数字

引用类型:Class

字符串

      let email="swift@163.com"
        
        let range=email.range(of: "@")!
        //拿到开始位置
        let suffix=email.substring(from: range.upperBound)
        //拿到结束位置
        let prefix=email.substring(to: range.lowerBound)
        //获取从开头到@前面的位置
        let newRange=Range(uncheckedBounds: (email.startIndex,range.lowerBound))
print(email[newRange])//输出这一段的信息
    //获取从@到结尾的位置
        let oldRange=Range(uncheckedBounds: (range.upperBound,email.endIndex))
        print(email.characters.count)
//输出这一段的信息
        print(email[oldRange])

数组初始化

class SwiftClass: NSObject {
    @objc(foo)
    func foo()
    {
        //初始化一个数组
        let titles:[String]=["发现音乐","我的音乐","朋友","账号"]
        //初始化一个数组
        let emptyArray=[String]()
        //重复发现映月这个词4次初始化一个这样的数组
        let a = Array(repeating: "发现映月", count: 4)
        //将数组a和数组titlesp拼接成一个数组
        let b=a+titles
        
        print(b)
        
        
    }
}

Array遍历

        //普通的数组遍历
        for title in titles{
            print(title)
        }
        //带下标的数组遍历
        for (index,title) in titles.enumerated() {
            print(index,title)
            print(titles[index])
        }